BAKER BROS ADVISORS LLC 03/31/2013 795,803 555,636 231.35 8,467
ORBIMED ADVISORS LLC 03/31/2013 774,000 774,000 New 8,235
774,000 new position folks dont give away your shares.
Smart funds are collecting whatever they can get their hands on and they will be adding..
These guys are fundamental long term investors. They are looking to get millions of shares in INSM over time. They are not looking for 30% returns but 1-3x returns. Obviously if it is a good idea they will share with their friends at other funds - that is how the biz works....=)